1. Field of the Invention
The present invention relates to a vehicle power generation system mounted on a vehicle having an internal combustion engine as a travel drive power source, and including a fuel cell which runs on ethylene glycol or the like separated from fuel of the internal combustion engine to generate electric power.
2. Description of Related Art
In recent years, a battery mounted on a vehicle tends to be easily overdischarged when the vehicle is parked, which is due to an increase of the number of vehicle-mounted accessories and their functions. This causes a consumption current (dark current) of the battery when the vehicle is parked to increase. In addition, a remaining capacity of the vehicle battery decreases with time by self-discharge while the vehicle is parked. The decrease of the remaining capacity is promoted even when the vehicle is running, if an electrical load increases to such an extent that a balance between charging and discharging of the vehicle battery is lost.
In a vehicle in which a fuel cell is mounted, the vehicle battery of the vehicle can be charged by use of this fuel cell even when a vehicle engine is stopped. However, in this case, fuel supply to the fuel cell has to be secured. As a solution to this, the applicant of this application has proposed to use methanol contained in window washer fluid as fuel for the fuel cell (refer to Japanese Patent Application Laid-open No. 2005-158335).
However, although methanol is suitable for use as the fuel for a direct-fuel type fuel cell, it possesses toxicity. In addition, since methanol is small in molecular size, and accordingly it easily permeates through an electrolyte membrane included in the fuel cell, which causes lowering of a generation voltage of the fuel cell. It is possible to prevent methanol from permeating through the electrolyte membrane by increasing a thickness of the electrolyte membrane. However, in this case, an internal electrical resistance of the fuel cell increases. Furthermore, if a user of the vehicle puts different fluid from the window washer fluid in a window washer fluid reservoir, it becomes difficult for the fuel cell to generate electric power.